Yamanashi Taro, Uchiyama Takeshi, Saito Shunya, Higashi Taiki, Ikeda Hayato, Kikunaga Hidetoshi, Yamagami Mutsumi, Ishimaru Yasuhiro, Uozumi Nobuyuki
Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan.
Research Center for Electron Photon Science, Tohoku University, Sendai, 980-0826, Japan.
Stress Biol. 2022 Dec 12;2(1):52. doi: 10.1007/s44154-022-00074-x.
Potassium (K) is a major essential element in plant cells, and KUP/HAK/KT-type K transporters participate in the absorption of K into roots and in the long-distance transport to above-ground parts. In Arabidopsis thaliana, KUP9 is involved in the transport of K and Cs in roots. In this study, we investigated KUP9 function in relation to the K status of the plant. The expression of KUP9 was upregulated in older leaves on K-depleted medium, compared to the expression of the other 12 KUP genes in the KUP/HAK/KT family in Arabidopsis. When grown on low K medium, the kup9 mutant had reduced chlorophyll content in seedlings and chlorosis in older rosette leaves. Tissue-specific expression of KUP9 determined by KUP9 promoter:GUS assay depended on the K status of the plants: In K sufficient medium, KUP9 was expressed in the leaf blade towards the leaf tip, whereas in K depleted medium expression was mainly found in the petioles. In accordance with this, K accumulated in the roots of kup9 plants. The short-term K tracer measurement showed that K was transferred at a lower rate in roots and shoots of kup9, compared to the wild type. These data show that KUP9 participates in the distribution of K in leaves and K absorption in roots under low K conditions.
钾（K）是植物细胞中的一种主要必需元素，KUP/HAK/KT型钾转运蛋白参与钾向根中的吸收以及向地上部分的长距离运输。在拟南芥中，KUP9参与根中钾和铯的运输。在本研究中，我们研究了KUP9与植物钾状态相关的功能。与拟南芥KUP/HAK/KT家族中的其他12个KUP基因的表达相比，KUP9在低钾培养基上的老叶中的表达上调。在低钾培养基上生长时，kup9突变体幼苗中的叶绿素含量降低，莲座老叶出现黄化。通过KUP9启动子：GUS分析确定的KUP9的组织特异性表达取决于植物的钾状态：在钾充足的培养基中，KUP9在叶片向叶尖的部位表达，而在低钾培养基中，表达主要在叶柄中发现。与此一致的是，kup9植株的根中积累了钾。短期钾示踪测量表明，与野生型相比，kup9的根和地上部中钾的转运速率较低。这些数据表明，KUP9在低钾条件下参与叶片中钾的分布和根中钾的吸收。
